1. Field of the Invention
This invention relates to a plasma generating device using micro-waves.
2. Description of Prior Arts
Micro-wave plasma has been used in the field of chemical vapor deposition (CVD) of semiconductor wafers, plasma usher, etching, and so forth. As has been well known, `plasma` is meant by ionized gas containing ions, electrons, neutron particles, and being neutral as a whole. Depending on the purpose of its use, the micro-wave power, the gas flowrate, and the gas pressure are varied. In recent years, demands have become rapidly high in respect of increase in size and area of the semiconductor wafers. For coping with such demands, there has arisen a need for the plasma generating section to have a high withstanding voltage.
As the insulating tube for flowing the gas in the plasma generating section, use is made of quartz. Owing to its exhaustion and consumption by the plasma generation, this insulating tube is required to have easy exchangeability as a supply material. While this insulating tube poses no problem so far as the micro-wave power is low, if and when the power of 1 KW or higher is used, there is not a small possibility, wherein the insulating tube is broken due to generation of heat during its use. On account of this, cooling of the insulating tube takes an important role. For the method of cooling, there has so far been employed various expendients such that a water cooling pipe is spirally wound on and around the insulating tube or a water layer is provided thereon. As the result, the structure of the plasma generating device is liable to be complicated.
In view, therefore, of the abovementioned points of problems, it is the primary object of the present invention to provide a micro-wave generating device of a simple construction and with good cooling effect of the insulating tube.
With a view to attaining the abovementioned object, the present invention is directed to provide the micro-wave plasma generating device of a type which generates the plasma by introduction of a processing gas into the insulating tube which transverses through a micro-wave waveguide, and is characterized in that metal wire or metal rod is spirally wound on and around the insulating tube.
The foregoing object, other objects as well as the detailed construction and function of the micro-wave plasma generating device according to the present invention will become more apparent and understandable from the following detailed description of the invention, when read in conjunction with the accompanying drawing.